Corrosion In Artificial Saliva Research Articles

Effect of Artificial Saliva Modification on the Corrosion Resistance and Electronic Properties of Bego Wirobond® C Dental Alloys

Wirobond® C is a commercial dental casting alloy suitable for the fabrication of crowns, bridges, and metal ceramic restorations. This study aims to investigate the effect of ready-to-use Listerine® and Meridol® mouthwashes and sodium fluoride on the resistance of CoCrMo dental alloys to electrochemical corrosion in artificial saliva at 37 °C. SEM, EDS, SKP, and microhardness investigations were carried out to characterize the material under study. The in vitro corrosion resistance of the CoCrMo alloy was conducted using the open-circuit potential method, electrochemical impedance spectroscopy, and anodic polarization curves. The presence of Co 59.8(8) wt.%, Cr 31.5(4) wt.%, and Mo 8.8(6) wt.% was confirmed. The CoCrMo alloy was characterized by a Vickers microhardness value of 445(31) µHV0.3. Based on the EIS data, the capacitive behavior and high corrosion resistance of the CoCrMo alloy were revealed. The kinetics of pitting corrosion in the artificial saliva were lower after being modified with NaF, Listerine®, and Meridol® mouthwashes. The potentiodynamic characteristics revealed the passive behavior of the CoCrMo alloy in all solutions. Based on the SKP measurements of the CoCrMo alloy after corrosion tests, the effect of artificial saliva modification on the electronic properties of Bego Wirobond® C dental alloy was found.

Effect of Artificial Saliva Modification on Pitting Corrosion and Mechanical Properties of the Remanium®-Type Orthodontic Archwire.

The pitting corrosion of orthodontic apparatus elements in the oral environment is an interest of both clinicians and scientists dealing with the assessment of the biocompatibility of medical materials. This work presents a study on the effect of ready-to-use Listerine® and Meridol® mouthwashes and sodium fluoride on the resistance of the commercial Remanium®-type orthodontic archwire to pitting corrosion in artificial saliva at 37 °C. XRD, SEM, EDS, mechanical properties, and microhardness measurements were used to characterize the archwire. The in vitro corrosion resistance of the archwire was examined using the open-circuit potential method, electrochemical impedance spectroscopy, and anodic polarization curves. The physicochemical characteristics confirmed the presence of a bi-phase alloy with a mixed austenite/ferrite structure containing Fe 74.4(7) at.%, Cr 18.4(4) at.%, and Ni 7.2(4) at.%. The Fe-Cr-Ni alloy was characterized by high tensile strength and Vickers microhardness. EIS revealed the capacitive behavior with high corrosion resistance. It was found that the kinetics of pitting corrosion in the artificial saliva decreased in the presence of NaF and mouthwashes. The potentiodynamic characteristics confirmed the decrease in susceptibility to pitting corrosion after the modification of artificial saliva. The pitting corrosion mechanism of the self-passive oxide layer on the surface of the Fe-Cr-Ni electrode in the biological environment containing chloride ions was discussed in detail. Mechanical properties after corrosion tests were weakened.

Impact of Fluoride on the Corrosion Pattern of Pure Titanium and Titanium Alloy Combined with Nickel-Chromium Alloy and Gold Alloy: An In-vitro Study

Introduction: Currently, Fluoride ions are added to commercially available tooth paste, mouth washes and cariostatic gels for their prophylactic action. However, the preventive effect may also be accompanied by the corrosive activity, through infiltration of fluoride-containing saliva in the contact between crowns and bridges or into the implant supported structure. Aim: To evaluate the corrosion action of Sodium Fluoride (NaF) on Pure Titanium (PT) and its alloy coupled with NickelChromium (Ni-Cr) alloy (NC) and Gold (Au) Alloy (GA). Materials and Methods: This in-vitro study was conducted in the Department of Prosthodontics at Central Electrochemical Research Institute, Karaikudi, Tamil Nadu, India. The duration of the study was six months, from April 2010 to September 2010. A total of 48 specimens were categorised under four groups. The four groups included for the study were pure group I (PT+GA), group II (PT+NC alloy), group III {Titanium Alloy (TA)+GA) and group IV (TA+NC alloy}. The specimens under each group were divided into half and were immersed in 100 mL of either artificial saliva or artificial saliva with 1000 Parts Per Million (ppm) fluoride. The current was passed at a scanning rate of 1800 mV/hour for 60 minutes and changes in corrosion potential were observed. The elemental release analysis test was conducted by using inductively coupled plasma-mass spectrometry to quantitatively analyse the elements (metal ions) released in the test solution from the galvanic coupling alloys. In order to evaluate the corrosion behaviour, the surfaces of the specimens were examined with an optical microscope (Eclipse LV100D, Nikon, USA). Analysis of Variance (ANOVA) was done for intergroup comparison. Statistical significance was set at 5%. Results: The mean value of corrosion of PT+GA and PT+NC was 13 μg/cm2 and 27 μg/cm2 respectively. The mean value of corrosion of TA+GA and TA+NC was 12 μg/cm2 and 24 μg/cm2 respectively, in artificial saliva without sodium fluoride. In the presence of sodium fluoride, the mean value of corrosion of PT+GA and PT+NC was 17 μg/cm2 and 60 μg/cm2 respectively, and the mean value of corrosion of TA+GA and TA+NC was 15 μg/cm2 and 41 μg/cm2 . The PT and TA specimens coupled with NC alloy specimens showed more corrosion in saliva either with or without sodium fluoride compared to GA. Conclusion: The NC alloy specimens coupled with PT and TA specimens showed severe pitting corrosion in artificial saliva containing sodium fluoride.

Experimental Study Regarding the Behavior at Different pH of Two Types of Co-Cr Alloys Used for Prosthetic Restorations.

Cobalt-chromium (Co-Cr) alloys are widely utilized in dentistry. The salivary pH is a significant factor, which affects the characteristics and the behavior of dental alloys through corrosion. This study aimed to evaluate the corrosion behavior in artificial saliva with different pH values (3, 5.7, and 7.6) of two commercial Co-Cr dental alloys manufactured by casting and by milling. Corrosion resistance was determined by the polarization resistance technique, and the tests were carried out at 37 ± 1 °C, in Carter Brugirard artificial saliva. After the electrochemical parameters, it can be stated that the cast Co-Cr alloy has the lowest corrosion current density, the highest polarization resistance, and the lowest speed of corrosion in artificial saliva with pH = 7.6. In the case of milled Co-Cr alloy, the same behavior was observed, but in artificial saliva with pH = 5.7, it recorded the most electropositive values of open circuit potential and corrosion potential. Although both cast and milled Co-Cr alloys presented a poorer corrosion resistance in artificial saliva with a more acidic pH value, the milled Co-Cr alloy had better corrosion behavior, making this alloy a better option for the prosthetic treatment of patients suffering from GERD.

Diferenciação oxidativa em dispositivos temporários de ancoragem de Ti6Al4V e aço 316L – estudo piloto

The aim of this pilot study was to test the hypothesis that temporary anchoring devices (TADs) made of 316L steel are more resistant to corrosion even in fluorine environment than DATs manufactured in addition to titanium alloys, for this Potentiostat electrochemical measurements were performed. Materials and Methods: Four pieces of each material were tested in each test set, an application of Fusayama artificial saliva was used as an electrolytic solution in this study of in vitro corrosion, without fluorine in its composition and in a second moment with 1500ppM of fluorine in its composition. In the test, a cathodic polarization was performed by increasing this voltage for 5 minutes or until the corrosion pins were obtained. In artificial saliva containing up to 1500ppmF- this test was repeated with new samples of each material in artificial saliva solution without fluorine. Results: The results of the induction current scale were inserted into OriginPro8 software for making value graphs. As there was a small number of samples, in order not to violate the study’s reliability no statistical test was performed. Among all metal alloys currently used the Ti6Al4V alloy showed good resistance to corrosion in artificial saliva. However, the corrosion of these alloys occurs in contact with high fluorine concentration, unlike 316L steel alloy, which in addition to corrosion makes surface passivation.

Effect of Four Manufacturing Techniques (Casting, Laser Directed Energy Deposition, Milling and Selective Laser Melting) on Microstructural, Mechanical and Electrochemical Properties of Co-Cr Dental Alloys, Before and After PFM Firing Process

The objective of this study was to compare four manufacturing processes of Co-Cr dental alloys: casting (CAST), computer aided design/computer aided manufacturing (CAD/CAM) milling (MILL), selective laser melting (SLM), and laser directed energy deposition (LDED). Comparison included microstructural, mechanical, and electrochemical analyses. Half of the samples obtained were heat treated to simulate the porcelain fused to metal (PFM) firing process, and the metal real state in an oral environment. Co-Cr dental alloys manufactured via casting, LDED, milling, and SLM techniques presented evident differences in their mechanical properties. However, their electrochemical performances were similar, with high resistance to corrosion in artificial saliva, in both aerated and deaerated media (corrosion rate under 4 microns per year). LDED and milling materials showed the highest modulus of toughness, and gave improved results in comparison with CAST and SLM techniques (p < 0.05). The LDED process could be implemented in the manufacturing of the restorative dental industry, with a high overall performance, competing directly with the best quality techniques, and reducing their disadvantages.

SEM/EDS ANALYSES ON SHAPE MEMORY ALLOY SUBJECTED TO ELECTROCHEMICAL CORROSION

The aim of the present paper was to investigate the modifications occurred in the Ti- based shape memory alloy subject to electrochemical corrosion in artificial saliva. By 2D and 3D microscopy and by qualitative determinations of the luminous variation we could notice the effects of electrochemical corrosion tests on the surface of the metallic material, and by EDS determinations (Line and Mapping modes) of the surface chemical composition we could determine the chemical modifications produced following the corrosion tests.

SEM/EDS analyses on shape memory alloy subjected to electrochemical corrosion

The aim of the present paper was to investigate the modifications occurred in the Ti-based shape memory alloy subject to electrochemical corrosion in artificial saliva. By 2D and 3D microscopy and by qualitative determinations of the luminous variation we could notice the effects of electrochemical corrosion tests on the surface of the metallic material, and by EDS determinations (Line and Mapping modes) of the surface chemical composition we could determine the chemical modifications produced following the corrosion tests.

Effect of Heat Treatment on Corrosion Behavior of Duplex Stainless Steel 2507 in Artificial Saliva

The effect of heat treatment of duplex stainless steel 2507 on its corrosion in artificial saliva is studied. The microstructure of the steel is analyzed using scanning electron microscopy and x-ray diffractometry. The hardness and the corrosion resistance of the alloy are determined and potentiodynamic measurements are performed. An optimum mode of heat treatment is suggested for raising the corrosion resistance of steel 2507.

Influence of electrochemical corrosion tests in an artificial environment on the chemical composition of a Co-Cr-Mo dental alloy

The goal of this study consists in the determination of structural modifications produced in a non-noble alloy intended for metal components of the skeletonized removable partial dentures following electrochemical corrosion in artificial saliva. The behavior to electrochemical corrosion was shown by the microstructural and chemical analysis by means of an electron scanning microscope fitted with an EDAX electron detector. We noticed that on the analyzed surface of Co-Cr-Mo alloy (Remanium GM 800, Dentaurum) that the Co and Mo elements lost their initial mass percentage, whereas others like Si increased their mass percentage with a very small quantity, a fact indicating the corrosion of Co and Mo elements and a better resistance of silicon. Following the determinations made, we may affirm that Co-Cr-Mo alloy (Remanium GM 800, Dentaurum) has a behavior to electrochemical corrosion in artificial saliva of generalized type and preferential by phases, with oxidization on the entire surface of the material and the formation of a superficial corrosion layer on the phase of matrix type.

Microstructural Analysis of Ti-Based Shape Memory Alloys Following the Electrochemical Corrosion in Artificial Saliva

The investigations carried out aimed to highlight the structural modifications occurred in the Ti-based shape memory alloys subject to electrocorrosion in Afnor artificial saliva. The behavior to corrosion was highlighted by fast electrochemical tests, mainly by dynamic potentiometry. From the microstructural analysis we noticed that the specimens of the two Ti-based shape memory alloys show traces of “pitting” corrosion on their surface of diverse sizes, a fact that will raise issues in terms of cytotoxicity due to the corrosion products released.

Impact Of Strain In Drawing Process And Surface Modification On Resistance To Electrochemical Corrosion Of Wires Used In Dentistry

Abstract The study presents the results of research into the impact of strain in cold drawing and surface modification treatment on corrosion properties of wires made of X10CrNi 18-8 steel used in maxillofacial surgery. Scanning microscopy enabled to make images of the surface of wires after drawing process as well as after surface modification treatment. Resistance to electrochemical corrosion was evaluated on the ground of registered anodic polarisation curves in artificial saliva. In order to evaluate physical and chemical properties of the surface, electrochemical impedance spectroscopy was performed. Test results show deterioration of corrosion properties of wires along with strain taking place in drawing process. It was proved that electrochemical polishing and chemical passivation caused sudden increase of resistance of wires made of stainless steel to pitting corrosion in artificial saliva.

Corrosion in artificial saliva of a Ni-Cr-based dental alloy joined by TIG welding and conventional brazing

Fixed prosthesis and partial dental prosthesis frameworks are usually made from welded Ni-Cr-based alloys. These structures can corrode in saliva and have to be investigated to establish their safety. The purpose of this study was to evaluate the corrosion behavior of joints joined by tungsten inert gas (TIG) welding and conventional brazing in specimens made of commercial Ni-Cr alloy in Fusayama artificial saliva at 37°C (pH 2.5 and 5.5). Eighteen Ni-Cr base metal specimens were cast and welded by brazing or tungsten inert gas methods. The specimens were divided into 3 groups (base metal, 2 welded specimens), and the composition and microstructure were qualitatively evaluated. The results of potential corrosion and corrosion current density were analyzed with a 1-way analysis of variance and the Tukey test for pairwise comparisons (α=.05). Base metal and tungsten inert gas welded material showed equivalent results in electrochemical corrosion tests, while the air-torched specimens exhibited low corrosion resistance. The performance was worst at pH 2.5. These results suggest that tungsten inert gas is a suitable welding process for use in dentistry, because the final microstructure does not reduce the corrosion resistance in artificial saliva at 37°C, even in a corrosion-testing medium that facilitates galvanic corrosion processes. Moreover, the corrosion current density of brazed Ni-Cr alloy joints was significantly higher (P<.001) than the base metal and tungsten inert gas welded joints.

Investigation of the electro-chemical corrosion of laser-melted layers of stainless steel in artificial saliva

Austenitic stainless steel is one of the materials commonly used for manufacturing of orthodontic appliances and brackets. In this study, samples of AISI 321 (EN X6CrNiTi 18-10) steel in initial condition and after laser surface melting were investigated in artificial saliva with pH 5.6. Two tests were conducted: measurement of open circuit potentials (free potentials) Ef until reaching steady state potentials Ess and potentiodynamic anodic polarisation. The samples’ surface was characterised by SEM, and EDX analysis was also done. Small amount of pits were observed on the surface of all samples – untreated and laser-melted layers as well. The steady state potential of the base metal was about +238 mV, while that of the laser-melted layers was approximately 50 mV lower. The pitting potentials Epit of the laser-treated samples were lower than those of the untreated stainless steel (+802 mV). It was established that the laser-melted surface layers of stainless steel are more susceptible to pitting corrosion in artificial saliva with higher acidity than those of the base metal.

Corrosion Behavior of Titanium in Artificial Saliva by Lactic Acid.

As one of the main products produced by oral microorganisms, the role of lactic acid in the corrosion of titanium is very important. In this study, the corrosion behavior of titanium in artificial saliva with and without lactic acid were investigated by open-circuit potentials (OCPs), polarization curves and electrochemical impedance spectroscopy (EIS). OCP firstly increased with the amount of lactic acid from 0 to 3.2 g/L and then tended to decrease from 3.2 to 5.0 g/L. The corrosion of titanium was distinctly affected by lactic acid, and the corrosion rate increased with increasing the amount of lactic acid. At each concentration of lactic acid, the corrosion rate clearly increased with increasing the immersing time. Results of scanning electron microscopy (SEM) also indicated that lactic acid accelerated the pitting corrosion in artificial saliva. A probable mechanism was also proposed to explain the experimental results.

Influence of surface layer on mechanical and corrosion properties of nickel-titanium orthodontic wires

To analyze the effect of various coating formulations on the mechanical and corrosion properties of nickel-titanium (NiTi) orthodontic wires. Uncoated, rhodium-coated, and nitrified NiTi wires were observed with a three-point-bend test, surface roughness (Ra) measurement, scanning electron microscopy, energy dispersive spectroscopy, and electrochemical testing (open circuit potential, electrochemical impedance spectroscopy, and cyclic polarization scan). Differences in the properties of tested wire types were analyzed with analysis of variance and Tukey post hoc test. Uncoated and nitrified NiTi wires showed similar mechanical and anticorrosive properties, while rhodium-coated NiTi wires showed the highest Ra and significantly higher modulus of elasticity, yield strength, and delivery of forces during loading but not in unloading. Rhodium-coated NiTi wires also had the highest corrosion current density and corrosion potential, lowest impedance modulus, and two time constants on Bode plot, one related to the Rh/Au coating and the other to underlying NiTi. Working properties of NiTi wires were unaffected by various coatings in unloading. Nitrification improved corrosion resistance. Rhodium coating reduced corrosion resistance and pronounced susceptibility to pitting corrosion in artificial saliva because of galvanic coupling between the noble coating and the base alloy.

Preliminary Studies Regarding the Behaviour of New Titanium Implants

This paper presents a study concerning a new titanium-based product reached by the specific techniques of powder metallurgy. The product was tested in vitro to corrosion in artificial saliva and in vivo by biological inocuity on sheep and rats for biocompatibility. The chemical composition of artificial saliva solutions used for general corrosion tests were: Fusayama solution; Carter solution; Ericsson solution; Hank solution; Ringer solution. The exposure length was 48, 720, 1440 and 2784 hours. On the sheep, six titanium implants of purity 99.89%, sintered with microporosities and nanoporosities at the surface were administered. Function of implant location, three cm incisions in the skin was made in the following regions: retroscapular for subcutaneous implants, in the tibial diaphysis for the subperiostal implant and in the Latimus Dorsi region for the intramuscular implant. Three different lots of Wistar breed rats were used; the sintered 3.5/1.5 cm titanium implants were placed subcutaneously and intermuscles. Parameters of descriptive statistics were used to assess inflammatory reaction.

Cytocompatibility and electrochemical properties of Ti–Au alloys for biomedical applications

The purpose of this study was to develop Ti-Au alloys with a higher resistant to corrosion, better biocompatibility, and better mechanical properties than the commercially pure titanium and its alloys. Ti-Au alloys were designed with a gold content that ranged from 0 to 5.0 at % in steps of 1.0 at %. Properties of the alloys including chemical composition, microstructure, phase, hardness, electrochemical properties, and the cytotoxicity were investigated. Only the alpha phase existed in the Ti-Au alloys. The addition of gold to the titanium decreased the alpha to beta transformation temperature. The acicular alpha phase became thinner and the hardness value increased with increasing gold content. In the electrochemical tests, Ti-Au alloys had a higher resistant to corrosion than had pure titanium and did not exhibit pitting corrosion in artificial saliva. The cytotoxicities of the Ti-Au alloys were similar to that of pure titanium. Therefore, Ti-Au alloys could be used as biomaterials in the medical and dental fields.

Properties of titanium–silver alloys for dental application

The purpose of this study was to develop titanium-silver alloys with biocompatibility, high corrosion resistance, and low ion-release rate, and to evaluate the electrochemical properties of titanium-silver alloys in artificial saliva. Titanium-silver alloys with silver contents ranging from 0 to 4.5 at % in steps of 0.5 at % were designed. The alloys were arc melted, homogenized at 950 degrees C for 72 h, hot rolled to 2 mm in thickness, and finally solution heat treated at 950 degrees C for 1 h and quenched in water. Chemical compositions, phases, hardnesses, electrochemical properties, and the cytotoxicity of the alloys were investigated. The purity of titanium-silver alloys was maintained above 99.9%, because few impurities were introduced through their manufacture. In the case of alloys containing silver in the range 2.0-4.0 at %, the formation of an acicular alpha phase was observed inside the beta phase. The acicular phase got thinner with increasing amounts of silver. This means that silver is a beta-phase stabilizing element in titanium-silver alloys. The hardness value tended to rise with increasing silver content and increased largely over 3.5 at %, and the increase of the hardness value versus pure titanium was about 33%. It is believed that the substantial increases in hardness was due to the effects of solid solution strengthening and of alpha-beta phase transition. Moreover, titanium-silver alloys had higher corrosion resistances than pure titanium. These results mean that silver additions to titanium can improve alloy corrosion resistance. Passive current densities in the potentiodynamic polarization curves were dependent on the chemical compositions of the titanium-silver alloys. However, they did not show a linear relationship with respect to silver contents. Titanium-silver alloys did not show pitting corrosion in artificial saliva. It is believed that silver addition to titanium strengthened the passive film due to titanium dissolution induced by the different electromotive forces of titanium and silver. In the agar overlay test, the cytotoxicity of the titanium-silver alloys and of titanium were none or mild. In summary, titanium-silver alloys had higher mechanical properties and corrosion resistance than titanium, and toxicities that were similar to titanium. Therefore, it is recommended that titanium-silver alloys be adopted cautiously by the biomedical and dental fields.

Corrosion of gold alloys and titanium in artificial saliva.

Two types of gold alloys and one type of pure titanium have been submitted to corrosion in artificial saliva for periods of up to about 2 months. The release of copper, gold or silver from the gold alloys as well as titanium from the titanium matrix was measured with nuclear tracer technique. The physical/chemical state of the corrosion products of gold alloys referring to the ionic state or presence in particulate form has been examined retaining the particulate matter on a glass filter. Copper was observed to be mainly present in the ionic state. Considerable amounts of gold were observed to be retained on the glass filter explained by the presence of gold in particular form or as a component of a dispersed colloidal phase. The estimation of the release of titanium was registered by the tracer nuclide 46Sc assuming particulate matter to be deteriorated from the titanium surface.